I. Field of the Invention
This invention relates to a synchronizing mechanism for a mechanical oscillation system and more particularly to mechanical oscillation systems in clockwork drives.
II. Description of the Prior Art
Mechanical swinging or oscillating systems of clockwork drives of the type of the present invention perform damped oscillations, but must swing with constant amplitude for driving the clockwork. For this purpose, it is necessary that in each oscillation state, sufficient energy is supplied to compensate for the damping of the oscillating system. The relative motion between the inductors and the permanent magnets during the swinging movement results in an induced voltage in the inductors having a known curve for the type of clockwork drives considered here. At an appropriate polarity the current pulse which is induced in the second inductor, or the control coil, switches a transistor to its conducting state and permits a driving current to flow through the first inductor, or the drive coil which is connected to a power supply, as long as the control pulse lasts. According to the electrodynamic principle, the oscillatory movement is thereby maintained by supplying the energy required for maintaining the mechanical swinging or oscillation. For accomplishing these principles, known circuit arrangements have the common property that the energy needed for sustaining the oscillation is more effectively supplied by a short driving pulse which is generated each time the mechanical system is in the state of its greatest kinetic energy and this occurs when the mechanical swinger moves through its central position which lies between the two extreme positions.
Known clockwork drives with two inductors and two permanent magnets generate induced current or voltage pulses having a polarity which alternates when the mechanical oscillator changes its direction of movement. Thus, the driving pulse can only be delivered with each second induced control pulse so that the energy required for the oscillatory movement can be supplied each time only once per oscillation period. Thereby, a synchronization system having a standard frequency can be attained by variable proportioning of the energy supplied whereby, for example, the phase difference between the frequency of the mechanical oscillations and a standard frequency can be evaluated.
The precision of mechanical oscillation systems, which in most cases include a spiral spring for energy storage, depends first of all upon the characteristics of this spiral spring. Good mechanical oscillation systems operate with a deviation from an accurate rate amounting to one second per day per degree centigrade, which means that the inherent frequency or the resonant frequency of the oscillation system can change by a relatively high amount, depending upon the ambient temperature.
Quartz clocks which are very expensive and operate with directly controlled precision stepping motors run with an error of two minutes per year. At present, such an accuracy is not obtainable by the use of a mechanical oscillation system. It has been suggested that it might be possible to improve the accuracy of the rate, or to synchronize the electrodynamic clockwork drives, by a standard frequency generated by a quartz crystal; however, in most cases, such synchronization methods require particular mechanical details of the clockwork drive. For example, the clockwork drive must be set to a high rate or frequency which is then adjusted to the standard frequency at regular intervals. On the other hand, it is necessary to provide for special stop pins in the oscillation system which prevent oscillation beyond a predetermined value so that the range of possible frequency changes remains limited.